If I'm right Textastic for IOS have SFTP/FTP feature so for me is natural to have the same feature is a bigger version like the one on OSX.
If you prefer to use cyberduck use it. I prefer to have a feature and don't use it instead of missing the same feature.
This is only my 2 cent
I know that is possible to use also transmit for "mapping" SFTP drive but this feature will be great. Hope to see this soon. :-)
Customer support service by UserEcho